Function arguments

Input arguments themselves can be expressions. Some functions limit the type of expression that can be used as an input argument. The syntax specification tells you the number of data objects that can be used for one function evaluation.

There is always one output argument for a function. The specification of the output argument tells you: 1) the type of the result produced by a function and 2) the number of objects that can be produced when the function evaluates once.

You need to know the type of the output argument because functions can be used as other arguments. The result of a function can also be used to directly produce an output data object contained in an output destination.

When the map designer analyzes the interfaces of expressions in rules during the build process, it ensures that the output argument of a function matches the input argument it is used for. The analysis also checks the type of the output argument when that function is used to directly produce an output data object.

The output argument of a function specifies the result that the function produces for one evaluation. For example, one evaluation of the ABS function produces one positive number. One function evaluation might produce multiple outputs. If it does, the expression that contains that function might produce multiple evaluation sets.